The proposed work includes: 1. Skin testing of additional subjects for hypersensitvity to Actinomyces viscosus, Bacterionema matruchotii, Bacteroides melaninogenicus and Fusobacterium nucleatum to seek correlations between reactivity and severity of periodontal disease. Immunofluorescent studies of desquamative gingivitis for presence of in vivo fixed immunoglobulins and complement. Study of gingival tissue for presence of immune complexes by the Raji assay.